I am curious about the uv light and plants thread .. Some uv in the near visible spectrum is beneficial , or near neutral to plants; but uv at higher energies ( shorter wavelengths) is increasingly toxic to plants and animals as the wavelength shortens .What you want for plant growth and flowering is light in the red and blue spectrums of visible light and high PAR values ( Photosynthetically Active Radiation) . Lumens give a rough estimate of PAR values , but it is not the same .. Lumens refer more to perceived light brightness to the eye. CRI % values are approximations to the closeness to natural sunlight in colour spectrum. The higher the CRI , the closer to sunlight in spectral output.Plants generally use light in the 3000 to 4500 K range ( reddish/yellow) in flowering stages , and 6000K + for green growth . Most "full spectrum" lights in general use for plants and aquariums for both growth and eye appeal are the ones with about 6500 to 6700 K rating. A little toward the blue end of the light spectrum. Marine aquariums fo for much higher K values .. often over 10000K or more. Those are not needed or of any real value for plants though.I would guess the best lighting for the cactus terrarium would be a mix of the " warm white" ( 3500 to 4500K) fluorescent and 6500 t0 6700K "daylight " bulbs ( tubes)I really doubt the cacti would need temperatures much above normal room temperature to thrive. The extra bit of heat from the lighting should be more than enough.

Most reptile lamps I've seen are more ir (infra red) heat lamps for them to bask under .. There may be limited uv emitted by them, but it couldn't be a lot because it would be dangerous ( sunburn) to fatal .. genetic damage .. at higher exposures to higher frequency uv .

Forget about heat! Cacti may be dessert plants, but dessert means cool nights and most cati and succulents would prefer 40 degree F temperatures at night and during the winter. Hardly what this will give them.

Now if you want to grow rain forest or cloud forest plants, then use your terrarium.